ro 



fotary motion, and occasionally doubled themselves into a figure 

 of 8 shape ; they were about 300th of an inch in breadth. There 

 was a vesicle near the superior extremity, which showed a 

 suctorial-shaped disk ; at times when the animal was partially 

 constricted this projected from the superior extremity. The 

 body was filled with a yellowish opaque granular matter, show- 

 ing no trace of organization. These animalcules I sought in 

 vain for in the following summers, and it was only on the 15th 

 of last month I met with the same animal again, presenting 

 exactly the same appearance and occurring in equal profusion. 



It was some time after my first acquaintance with these that I 

 was reading an account of the development of the trematoda 

 in Streenstrup's* "Alternation and Generations," and was much 

 struck with the similarity of the animals there described, 

 under the head of " Cercaria Arma/a," and figured in tab. 3, 

 fig. la to 6a. So curious and wonderful are the transformations 

 these animals undergo before they assume their final fluke-shape, 

 the fearful ravages they commit in this form in destroying 

 thousands of sheep ; the sudden and mysterous spread of this 

 disorder in particular seasons, and the very slight knowledge we 

 possess of the larva forms and future development of these 

 creatures, all combine to render this subject one of surpassing 

 interest ; and although I shall not, unhappily, be able to add 

 much to what is already knowm, still I hope I may present it to 

 you in sufficient clearness that you may understand the delicate 

 nature of the enquiry. As before stated, on the 15th of last 

 month I again found the infusoria in great abundance ; this time 

 they appeared in a gentleman's fountain, where are large growths 

 of water lilies, aquatic snails, planaria, and leech. I found them 

 assuming the same swarming form on the underside of the water 

 lily leaves as on a former occasion, and they are in all respects 

 identical with those I discovered in 1866. I therefore wrote 

 again to Dr. Carpenter, mentioning my suspicion that they were 

 connected with the trematoda. Dr. Carpenter suggested I should 

 write and send specimens to Dr. Cobbold (the greatest English 

 authority on the entozoa.) I did so, but unfortunately Dr. 

 Cobbold writes that he has no time to examine the specimens, 

 and cannot offer an opinion. He, however, refers me to his 

 book on the entozoa, which I have consulted, without however 

 finding any additional light cast on the subject of my enquiry 

 from what I had read in Steenstrup's researches relating to the 

 various phases these animals undergo. I will now, however, 

 summarise these observations. 



The best known form of the numerous family of the 

 trematoda is the fluke or liver-place (Distoma hepaticum), or 

 Fasciola hepatica, entozoon which inhabit the livers of 

 sheep in particular situations, and especially in wet years, causing 

 the disease called the rot which has this year and last been most 



*See Ray's Society's Publication, 1845. 



